MiniSymposium on Hadrons and hadron Interaction in QCD

Introduction ○Recent observation of 2 -solar mass NSs * is providing a challenging problem

2 TNI 3 (1) NO Y TNI 2 1. 5 Y-mixing 1 with

But with Y ? Y R. B. Wiringa, V. Fiks and A. Fabrocini,

Efects of Universal 3 -body force repulsion ①It is natural to consider that the

Dramatic softening of EOS Necessity of “Extra Repulsion” EOS 1500 2 P TNI 3

Extended 2πΔ-Type 3 -body Force 　　 ; not universal B* ; T. Kasahara, Y.

EOS of Neutron Star Matter 400 300 (Me. V) Y-mixing 200 100 0 5

Repulsion from SJM-----flavor independent 　 (a) 2 B come in short distance (b) Deformation

Mass v. s. Central Density T. Takatsuka, S. Nishizaki and R. Tamagaki, AIP Conference

② hadron(H)+deconfined quark(Q) ○Hadrons are not a point-like particle but are composed of

3 -Window Model uncertain “known” unknown “known” P(x) H HQ Q (G-matrix) (NJL) (interpolation)

□ Approach by 3 -window model □ Some results

“H-Q crossover model” ・K. Masuda, T. Hatsuda and T. Takatsuka, Ap. J. 794

Summary (1) Hadron-Quark transition in NS cores generates a stiff EOS compatible with massive

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Mini-Symposium on Hadrons and hadron Interaction in QCD 2015 YITP, 2015. 3. 18 Maximum Mass of Neutron Stars with Hadron-Quark Transient Core T. Takatsuka (RIKEN; Prof. Emeritus Iwate Univ. ) □Introduction □Universal 3 -body force □Approach by 3 -Window Model □Some results ----------------------In collaboration with T. Hatsuda and K. Masuda

Introduction ○Recent observation of 2 -solar mass NSs * is providing a challenging problem how to reconcile the conflict between observations and theory. ・Massive NSs stiff EOS ! ・Dense matter theory (including phase transition ) Soft EOS ! #This contradiction is serious when we include the Y-mixing in NS cores ---- inndeed , “Hyperon Crisis”　----- Fig. ○There are two viewpoints (frameworks)of approach : ①　pure hadron(H) matter with hadron interactions (assuming that the point-like picture of hadrons is valid) ② hadron(H)+deconfined quark(Q) ( explicitly taking account of quark degrees of freedom) ○　As to the framework ① , Universal 3 -body force ○ ②　　　　　　　3 -window model for H-Q trans. 　 * Demorist et al. , Nature 467 (2010). 　Antoniadis et al. , Science 340 (2013).

2 TNI 3 (1) NO Y TNI 2 1. 5 Y-mixing 1 with Y 　× ●× ● 5 10 15 Strong Softening of the EOS

But with Y ? Y R. B. Wiringa, V. Fiks and A. Fabrocini, PR C 38 (1988) 1010. Y A. Akmal, V. R. Pandharipande and D. G. Ravenhall, PR C 58 (1998) 1804.

Efects of Universal 3 -body force repulsion ①It is natural to consider that the 3 -body force should be operative not only among NNN but also NNY, YYN and YYY. make an extended use of the 3 -body force of Illinoi-Group type also to {N+Y}-matter. 　Then it is found that strong softening is remarkably moderated. 　This is , however, a phenomenological way of approach. ②What is the origin? We make a step forward to microscopic description as Univ. 3 -body force = Short range part + Medium- long range part 3 -body repulsion from String-junction model (SJM) : Flavor- independent ! 2π-exchange via Isobar⊿(1232) excitation(Fujita-Miyazawa type) : extended to {N+Y} system

Dramatic softening of EOS Necessity of “Extra Repulsion” EOS 1500 2 P TNI 3 (NO Y) 1000 Y-mixing Mass TNI 3(NO Y) TNI 3 u (Y) TNI 3 u(Y) 1. 5 Universal 3 body force 500 1 TNI 3(Y) 0 5 10 15 5 10 As a review T. Takatsuka, Prog. Theor. Phys. Suppl. No. 156 (2004) 84.

Extended 2πΔ-Type 3 -body Force 　　 ; not universal B* ; T. Kasahara, Y. Akaishi and H. Tanaka, PTP Suppl. No. 56(1974)96

EOS of Neutron Star Matter 400 300 (Me. V) Y-mixing 200 100 0 5 10

Repulsion from SJM-----flavor independent 　 (a) 2 B come in short distance (b) Deformation (resistance) (c) Fusion into 6 -quark state (by R. Tamagaki) Prog. Theor. Phys. 119 (2008) 965. ○ Energy barrier (～ 2 Ge. V) corresponds to repulsive core of BB interactions

Mass v. s. Central Density T. Takatsuka, S. Nishizaki and R. Tamagaki, AIP Conference Proceedings 1011 (2008) 209.

② hadron(H)+deconfined quark(Q) ○Hadrons are not a point-like particle but are composed of quarks 　( gluons) and tend to loose their identity as the matter density increases 　　　　------- deconfinement effects ○Quark matter gets to have strong correlations and eventually quarks are confined Into hadrons as the density decreases. ○H-Q transition region is very uncertain due to the confine-deconfine effects 　 ○Our way of approach is to sandwitch the very uncertain HQ –EOS in between the H- and Q- EOSs relatively “well-known” ----- 3 -window model. ○Here our aim is, though phenomenological , to seek whether Q-matter is existent or Q-degrees of freedom is revealed in NS cores in the light of massive NS observations , just by using the fact that HQ-EOS shoud meet the H-EOS somewhere in low density side and the Q-EOS at high density side.

3 -Window Model uncertain “known” unknown “known” P(x) H HQ Q (G-matrix) (NJL) (interpolation) Deconfinement and confinement are concerned

□ Approach by 3 -window model □ Some results

“H-Q crossover model” ・K. Masuda, T. Hatsuda and T. Takatsuka, Ap. J. 794 (2013) 12; PTEP 073 D 01 (2013).

Summary (1) Hadron-Quark transition in NS cores generates a stiff EOS compatible with massive NSs(2 -solar-mass NSs), as far as q-degrees of freedom sets in at rather low density(e. g. due to percolation) and the Q-EOS is stiff(e. g. due to vector interractions) (2) So possible candidates to resolve a so-called “ two-solar mass problem”: ○ pure hadronic scheme Universal 3 -body force ○ hadron+quark scheme NSs with HQ transition core